package com.yzf.enterprise.common.utils;

import java.util.List;

/**
 * @author wangzhen
 * @Description: 对list分页工具
 * @date 2020/4/22 10:53
 */
public class PageUtil {
    /**
     * 对list分页
     * @param list
     * @param pageNo 页码
     * @param pageSize 每页多少条数据
     * @return
     */
    public static List startPage(List list, Integer pageNo, Integer pageSize) {
        if (list == null) {
            return null;
        }
        if (list.size() == 0) {
            return null;
        }
        Integer count = list.size(); // 记录总数
        Integer pageCount = 0; // 页数
        if (count % pageSize == 0) {
            pageCount = count / pageSize;
        } else {
            pageCount = count / pageSize + 1;
        }
        int fromIndex = 0; // 开始索引
        int toIndex = 0; // 结束索引
        if (pageNo != pageCount) {
            fromIndex = (pageNo - 1) * pageSize;
            toIndex = fromIndex + pageSize;
        } else {
            fromIndex = (pageNo - 1) * pageSize;
            toIndex = count;
        }
        List pageList = list.subList(fromIndex, toIndex);
        return pageList;
    }
}
